Ag对热电耦合作用下铝/钢摩擦焊接头界面组织演变的影响

Effect of Ag on Microstructure Evolution of Aluminum/Steel Friction Welding Joints Under Thermoelectric Coupling

目的解决铝/钢摩擦焊接头在热电耦合后失效的问题,探究过渡元素对热电耦合后接头力学性能与界面组织的影响机理。方法采用刷镀法在Q235钢棒端面添加过渡元素Ag并与1060纯铝棒进行连续驱动摩擦焊接,与未添加Ag的接头一起开展为期56 d、静载40 kg、高温300℃、直流60 A的热电耦合实验,对比分析热电耦合影响下未添加Ag与添加Ag两种接头力学性能与界面微观组织的变化。结果经过热电耦合处理后的接头界面发生脆断,其抗拉强度为原始接头的96.2%,伸长量为原始接头的28.9%,界面金属间化合物出现裂纹、孔洞等缺陷。添加过渡元素Ag后,接头抗拉强度为原始接头的98.2%,断裂部位为铝母材并出现颈缩,界面金属间化合物层未出现裂纹、孔洞等缺陷。结论在为期56 d、静载40 kg、高温300℃、直流60 A的热电耦合作用下,添加过渡元素Ag的铝/钢接头可以维持原始接头的力学性能和界面组织。

The work aims to solve the joint failure problem of Al/Steel friction welded joint after thermoelectric coupling,and explore the influence mechanism of transition elements on mechanical properties and interface structure of the joint after thermoelectric coupling.The transition element Ag was added to the weld faying surface of Q235 steel rods by brush plating,and was continuously driven friction welding with 1060 pure aluminum rods.The joint carried out thermoelectric coupling test for 56 days under load of 40 kg,high temperature of 300℃and DC 60 A with the joint without Ag.The mechanical properties and interface microstructure of the two kinds of joints under the influence of thermoelectric coupling were compared and analyzed.The results show that after the thermoelectric coupling treatment,brittle fracture occurs at the interface of the original joint.The tensile strength and the elongation are 96.2%and 28.9%of that of the original joint,respectively.There are cracks and holes in the intermetallic compound at the interface.After the addition of transition element Ag,the tensile strength of the joint is 98.2%of that of the original joint,and the fracture site is aluminum base material.The fracture site is aluminum base material with neck shrinkage,and there are no cracks,holes and other defects in intermetallic compound layer.Under the thermoelectric coupling effect of 40 kg static load,300℃and DC 60 A for 56 days,the aluminum/steel joints with transition element Ag can maintain the mechanical properties and interface structure of the original joint.